Globally, marine communities are experiencing gradual warming and extreme heatwaves causing species to shift in geographic range. As a result, the biological assemblages outside tropical latitudes are being reorganized or “tropicalized” as warm-affinity species become increasingly dominant and cool water species recede, with impacts on our economies, food supply, and health. In the Gulf of California, existing oceanographic discontinuities shape marine communities by creating different assemblages according to environmental affinities. In this study, we show how a known ecological boundary underwent a northward shift of 1.5° latitude because of an average 1 °C gradual warming over the last decade (2010–2020) and extreme marine heatwaves threefold more frequent. Such shift homogenized environmental conditions and reconfigured rocky reefs communities. Fish biomass decreased of 43%, whereas invertebrates, which recorded a 35% decrease in overall abundance, showed different community configurations depending on the climate regime. Stony coral species with warm water affinities increased with a reduction of cold-water species during the last El Niño. The long-term consequences of the tropicalization of these rocky reefs’ communities are still uncertain. This study underlines the importance of long-term monitoring of key habitats to quantify, predict, and adapt to future climatic stresses.

在全球范围内，海洋社区正在经历逐渐变暖和极端热浪，导致物种在地理范围内转移。结果，热带纬度以外的生物群落正在重组或“热带化”，因为亲热物种变得越来越占主导地位，冷水物种逐渐减少，对我们的经济、食物供应和健康产生影响。在加利福尼亚湾，现有的海洋不连续性通过根据环境亲和力创建不同的组合来塑造海洋群落。在这项研究中，我们展示了一个已知的生态边界如何由于过去十年（2010-2020 年）平均 1°C 逐渐变暖和极端海洋热浪频率增加了三倍而经历了北纬 1.5° 的移动。这种转变使环境条件同质化并重新配置了岩礁群落。鱼类生物量下降了 43%，而无脊椎动物的总丰度下降了 35%，根据气候状况显示出不同的群落结构。在上一次厄尔尼诺现象期间，具有温水亲和力的石珊瑚物种随着冷水物种的减少而增加。这些岩礁群落热带化的长期后果仍不确定。这项研究强调了对关键栖息地进行长期监测以量化、预测和适应未来气候压力的重要性。在上一次厄尔尼诺现象期间，具有温水亲和力的石珊瑚物种随着冷水物种的减少而增加。这些岩礁群落热带化的长期后果仍不确定。这项研究强调了对关键栖息地进行长期监测以量化、预测和适应未来气候压力的重要性。在上一次厄尔尼诺现象期间，具有温水亲和力的石珊瑚物种随着冷水物种的减少而增加。这些岩礁群落热带化的长期后果仍不确定。这项研究强调了对关键栖息地进行长期监测以量化、预测和适应未来气候压力的重要性。